Force HTTP/1.1 for tests that query demo.mapserver.org to workaround …

…current issue with it (#6858)

Co-authored-by: Even Rouault <even.rouault@spatialys.com>

maphttp.c

@@ -484,6 +484,8 @@ int msHTTPExecuteRequests(httpRequestObj *pasReqInfo, int numRequests,
       msDebug("Using CURL_CA_BUNDLE=%s\n", pszCurlCABundle);
   }
 
+  const char* pszHttpVersion = CPLGetConfigOption("CURL_HTTP_VERSION", NULL);
+
   /* Alloc a curl-multi handle, and add a curl-easy handle to it for each
    * file to download.
    */
@@ -545,6 +547,13 @@ int msHTTPExecuteRequests(httpRequestObj *pasReqInfo, int numRequests,
 
     unchecked_curl_easy_setopt(http_handle, CURLOPT_PROTOCOLS, CURLPROTO_HTTP|CURLPROTO_HTTPS );
 
+    if (pszHttpVersion && strcmp(pszHttpVersion, "1.0") == 0)
+        unchecked_curl_easy_setopt(http_handle, CURLOPT_HTTP_VERSION,
+                                   CURL_HTTP_VERSION_1_0);
+    else if (pszHttpVersion && strcmp(pszHttpVersion, "1.1") == 0)
+        unchecked_curl_easy_setopt(http_handle, CURLOPT_HTTP_VERSION,
+                                   CURL_HTTP_VERSION_1_1);
+
     /* Set User-Agent (auto-generate if not set by caller */
     if (pasReqInfo[i].pszUserAgent == NULL) {
       curl_version_info_data *psCurlVInfo;

msautotest/etc/mapserv.conf

@@ -2,6 +2,10 @@ CONFIG
   ENV
     MS_MAP_PATTERN "."
     MS_CONTEXT_PATTERN "ows_context\.xml"
+
+    # Workaround current issues with demo.mapserver.org with HTTP/2
+    CURL_HTTP_VERSION "1.1"
+
   END
   # following used by the mssql tests on Appveyor
   PLUGINS